This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. MHC class I-restricted cytotoxic T-lymphocytes (CTL) play an important role in controlling human immunodeficiency virus and simian immunodeficiency virus (SIV) infection. As a natural host of SIV, sooty mangabeys (Cercocebus atys;Ceat) are a valuable model for the study of AIDS pathogenesis. We have previously defined several immunodominant SIV-specific CTL epitopes in sooty mangabeys and shown that CD8-positive T lymphocytes inhibit SIV replication in vivo in naturally SIV-infected sooty mangabeys. In order to identify the MHC class I restriction of immunodominant CTL epitopes, we have cloned and characterized MHC class I genes of sooty mangabeys. These studies will facilitate evaluation of the role of CTL in maintaining nonpathogenic SIV infection in sooty mangabeys.